Production of nets, knitted fabrics and the like from synthetic resin threads



Jan. 13, 1959 s. o. LJUNGBO 2,868,676

PRODUCTION OF NE KNITTED FABRICS AND THE LIKE FROM SYNTHETIC RESIN THREADS Filed Ju1y-20, 1956 i//W 'am/ef# f@ 2 e l/a/D Ora/e yV/MMM rfx Unite PRODUCTIONl oF NETS; KNITTED" FABRICS ANDHTHE LIKE FROM SYNTHETIC RESINl THREADS i The present invention relates tothe: production of nets, knitted' fabrics and the like fromsyntheticresin threads, and more specifically relatesrt-o improved method of obtaining fixed knots and crossings'` between the threads in such nets or fabrics.

Threads made'of synthetic textilematerial frequently involve .the drawback of anexcessive surface smoothness causing slippage between the threadsin articles suchfasf netting, knitted textiles, etc. in'whichit `isvdesirable that the knots"-'or crossings shouldbe secured in 'Ia-"compara-l tively fixed interrelation.

Thisdifliculty has been met invariousrways in the past. specificationNo. 2,590f,5 86) thefilaments are coated--with a syntheticlresin adaptedy to adhere=to-thefilamentsfand? being compressible to a higher degree than the latter. One drawback" ofthis priori-method is that'fit relies solely on such bon-ding actionbetweenfilament and coating as is obtained by applying .the'coating in the form of a solutionoremulsionthe'solvents of which are incapable ofdiss'o'lving the filament or thread superficially. lWh'ere the`requirementsfoneffectiveness of the coatingjiare higher; such fas in"fishing` netsm-ad'e'bf uniiilar threads and required to be wetted',- the 'bondi'rigstrength between the-'filament and the coating will be unsatisfactoryA resulting in an impaired fixation of the knots in thelwetted nets.

Further prior methods (U. S. patent specification No. 2,251,508) rely on a roughening of the filament surfaces, which is accomplished by treating the filaments with a solvent for filament material and then removing this solvent, for instance by washing with a non-solvent. A similar result is obtained according to the British patent specification No. 391,480 by treating the filaments with a mixture of a solvent and a non-solvent. Both these methods result in a certain weakening of the filaments since, due to their comparatively low viscosity the solutions cannot be prevented from penetrating into the filament and causing a deep-attack thereon.

Still further prior methods are based on coating the filaments with a polymer dissolved in one or more solvents for the filament material, if desired in admixture with non-solvents, and then drying the filaments, if desired, in connection with a heat-treatment thereof. These methods, too suffer from the drawback that the thread will be weakened due to the fact that the solutions are able to attack the same already before, through evaporation, their viscosity has been increased suiciently to prevent deep-attacking of the threads.

In accordance with the present invention the drawbacks referred to can be overcome in the following manner: v

To the thread is applied, in a manner known per se, a solution comprising a high polymer miscible with the filament material, a solvent or solvents for the filament material, and a diluent or diluents. The terrn, Inis'cible According to` certain` prior methods(U.' Sr patentV States atenf"tit with Should bo understood-*io*moiihat tho two polyi portion Aof the same remains on thevthreads-afterthe- Furthermore,` the solvents should be presentin a suflicientlyvsmall proportionin the solution'to beincapablefof. causinganymix-ing or inter-fusion' of the material` in the superficial-layer of diluents Ahave evaporated.

the thread and the highv polymer applied thereto solely through the action of applyingthe solution.v and evapo-- rating the diluent. Instead such inter-fusion or welding action is effected by heating the threads, after the evaporation ofthefdiluent, to'=a-Usuiicient'vl high temperature to causethefpolymer'appl-iedtogether with the remaining solvent to be transferred `into a more or less liquid state. This lWill result ina'weld between the filament surface and the polymer which, when using proper proportions S of polymer and solvent,` will' be satisfactory without weakening the"thread.

Thefollowing examples illustrate'the method in" a non" coating on the surface of the thread. After 'evaporation' of the benzene, the thread is subjected' to heat treatment at C. for aperiod of 30 seconds by passing the same through a chamber having this temperature. It

may be suitable, in order to cause the thread toi-attain theproper' temperature as rapidlyy as possible,' to'y pass'the same,immediately'before or after its introduction into'v the heat treatment chamber, through a pool of fusedf metal (for instance Roses metal) having this,or asome-v what higher, temperature, for instance C. After allowing the thread to cool it may be wound on spools to be transferred to a netting process. After a net has been made of the thread, the knots therein are secured by a stretching operation in conjunction with, or subsequent to, the application thereto of a suitable solvent for the methacrylate co-polymer, for instance xylene, butyl acetate, etc. As an alternative, the net may be heated to 130 to 140 C. during the stretching operation. It is also possible to combine the two procedures.

It is not necessary to apply the thread coating high polymer in the forrn of a solution. Instead it may be applied in the form of an emulsion, the solvents for the filament material concerned being, in this case, either emulsied or dissolved in the liquid emulsifier. This is shown by the following examples:

Example 2 84 parts of a 50% aqueous emulsion of polybutyl methacrylate is mixed with the following suspension:

9 parts of cresol 9 parts of benzoic acid 0.6 part of sodium lauryl sulphate 0.2 part of sodium alginate 27 parts of Water The emulsion obtained is applied to a unilar polyamide thread, and the latter is subjected to drying and further treatment in a manner 'similar to that of EX- ample 1.

Example 3 25 parts of a 40% aqueous emulsion of polymethyl methacrylate is mixed with the following suspension:

3 parts of cresol 3 parts of benzoic acid 0.6 part of sodium lauryl sulphate 85 parts of water The emulsion obtained is applied to a multifilar polyamide thread which is then subjected to further treatment in a manner similar to that of Examples 1 and 2. In spite of the fact that the polymer applied has a hardness substantially greater than that of the filament material, it is found to adhere satisfactorily to the latter as well as to result in a positive fixation of the knots in netting manufactured from such threads.

Example 4 15% by weight of Ultramid 1C 10% by weight of benzyl alcohol 7% by weight of water 68% by weight of ethanol (Ultramid 1C is mixed polyamide of hexamethylene diamine adipate, e-caprolactam and 4,4diaminodicyclo hexyl methane adipate.)

The solution is used in a manner similar to that of the preceding example.

Example 15% polyvinyl formal 2% meta-acetaldehyde 13% acetic acid 12% benzoic acid l58% acetone This solution is used in a manner similar to that ofk fabrics a liquid composition containing at least one solvent for said polyamide, at least one liquid diluent incapable of dissolving the po-lyamide, and at least one polymer which is miscible with the polyamide and soluble in said solvent but insoluble in water, said solvent having a rate of evaporation which is suiciently lower than that of said diluent to cause the major portion of the solvent applied to remain on the threads after the diluent has evaporated therefrom, the solvent being used in a proportion which is insufficient, also after evaporation o-f the diluent, to effect interfusion of the polyamide of the thread and said polymer at normal temperatures, said polyamide threads, nets and knitted fabrics after evaporation of the diluent being subjected'to a heat treatment whereby such interfusion is effected in the presence of the remaining solvent.

2.A A process as claimed in claim 1, wherein said liquid composition is a homogeneous solution, the diluent being miscible with the solvent and the polymer being dissolved in said mixture.

3. A process as claimed in claim l, wtherein said liquid composition is a mixture of the solvent and the diluent miscible therewith, the polymer being dispersed in said liquid mixture.

4. A process as claimed in claim 1, wherein said liquid composition is a dispersion of the polymer and the s01- vent therefor in said diluent.

5. A process as claimed in claim 1, wherein the heating is effected at a temperature of from C. to C. v

6. A process as claimed in claim 1, wherein the polymer is selected from the group consisting of polymethyl methacrylate, polybutyl methacrylate and co-polymerisates of methyl methacrylate and butyl methacrylate.

References Cited in the le of this patent UNITED STATES PATENTS 2,251,508 Watson Aug. 5, 1941 2,590,586 Thompson et al. Mar. 25, 1952 2,639,249 Gurin et al. May 19, 1953 2,790,736 McLaughlin et al. Apr. 30, 1957 FOREIGN PATENTS 391,480 Great Britain Apr. 21, 1933 685,623 Great Britain Jan. 7, 1953 

1. A PROCESS FOR TREATING POLYAMIDE THREADS AND NETS AND KNITTED FABRICS MADE THEREFROM WITH A VIEW TO OBTAIN SLIP-FREE KNOTS AND CROSSINGS BETWEEN THE THREADS, WHICH COMPRISES APPLYING TO SAID THREADS, NETS AND KNITTED FABRICS A LIQUID COMPOSITION CONTAINING AT LEAST ONE SOLVENT FOR SAID POLYAMIDE, AT LEAST ONE LIQUID DILUENT INCAPABLE OF DISSOLVING THE POLYAMIDE, AND AT LEAST ONE POLYMER WHICH IS MISCIBLE WITH THE POLYAMIDE AND SOLUBLE IN SAID SOLVENT BUT INSOLUBLE IN WATER, SAID SOLVENT HAVING A RATE OF EVAPORATION WHICH IS SUFFICIENTLY LOWER THAN THAT OF SAID DILUENT TO CAUSE THE MAJOR PORTION OF THE SOLVENT APPLIED TO REMAIN ON THE THREADS AFTER THE DILUENT HAS EVAPORATED THEREFROM, THE SOLVENT BEING USED IN A PROPORTION WHICH IS INSUFFICIENT, ALSO AFTER EVAPORATION OF THE DILUENT, TO EFFECT INTERFUSION OF THE POLYAMIDE OF THE THREAD AND SAID POLYMER AT NORMAL TEMPERATURES, SAID POLYAMIDE THREADS, NETS AND KNITTED FABRICS AFTER EVAPORATION OF THE DILUENT BEING SUBJECTED TO A HEAT TREATMENT WHEREBY SUCH INTERFUSION IS EFFECTED IN THE PRESENCE OF THE REMAINING SOLVENT. 